Low friction fabric material



F eb. 6, 1962 c. s. WHITE LOW FRI'CTION FABRIC MATERIAL Original FiledNov. 4, 1955 2 Sheets-Sheet 1 INVENTOR. 6247/65 5 '/zze Feb. 6, 1962 c.s. WHITE 3,019,821

Low FRicTIoN FABRIC MATERIAL Original Filed Nov. 4, 1955 2 Sheets-Sheet2 INVENTOR, CZdm/@s M/zfe 3,019,821 EGW FRKCTHON FABRIC MATERIAL CharlesS. White, 30007 Lahser Road, Birmingham, Mich.

riginai application Nov. 4, i955, Ser. No. 544,945, now Patent No.2,804,386, dated Sept. 3, 1957. Divided and this application .iuly 31,1957, Ser. No. 677,175

3 Claims. (Ci. 139-420) This invention relates to low frictionmaterials, and more particularly relates to a method for making and thefabrics which result from the use of such method and materials, and is adivision of Serial No. 544,945, filed November 4, 1955, now U.S. PatentNo. 2,804,886, for LOW Friction Fabric Material.

Low friction plastic materials have had very limited use as bearings,seals, pistons and the like, for different reasons, some of which arefailures at low temperatures, cold iiow, change in physicalcharacteristics under heating and pressure, and lack of bondingcharacteristics.

The present invention primarily employs plastic materials whichthemselves have low friction characteristics, and is based on thediscovery that unexpectedly useful low friction surfaces are produced ifplastic materials having relatively low friction characteristics areemployed in the form of bers. A supporting surface is provided whichretains the fibers in position to resist cold flow during the period ofrelative motion between the surface carrying the low friction materialand the opposed surface when the surfaces are loaded. Various attemptshave been made to support the low friction materials so as to resistcold ow during use and due to the simplicity of handling and ease inmanufacturing, the present invention contemplates the employment of thefibers in a woven form. By this means the fibers are disposed andsupported so as to be substantially uniformly distributed in or on asupporting Surface woven into the fabric.

The compound fabric material having the low friction fibers is bonded toa body made from suitable materials to form bearings, seals, pistons andthe like. The body material which supports the uniformly distributedfibers may vary substantially, that is to say, such material may bethermosetting and thermoplastic resins, such as phenolaldehyde resinsincluding particularly phenol formaldehyde resins, urea-formaldehyderesins, polyester resins, elastomeric materials including natural andsynthetic rubbers and the urethanes. For application such as bearings orseals it will be apparent that the body material which is selected forany particular application must be one which has the ability to resistdeformation and to retain its shape and properties under the temperatureconditions resulting from use. It is therefore advisable to select ahigh temperature resistant material, preferably of the thermosettingtype, such as phenol formaldehyde resins. It is to be understood thatconventional fillers and tensile reinforcing fibers for such resinousmaterials may beincorporated if desired and are advisable where theresult# ing structure is to be subjected to relatively high unit.pressures during use. For the worst conditions normallyr encountered inbearing and sealing applications, glass fiber filled resins areespecially satisfactory.

Fibers having low friction characteristics which have been found to besatisfactory for the purposes of this invention include the polyamideresins marketed under the name of nylon, the polyester resins marketedunder the name Daeron, polyethylene, the polymeric liuorocarbon resinsincluding tetrafluoroethylene, marketed under the trade name Teflon, andthe monochlorotrifiuoroethylene resins marketed under the vtrade namesof Kel-F and Fluorothene, available from M. W. Kellogg Co. and

Union Carbide and Carbon Corp., respectively. For cerice tainapplications, vinyl chloride resin fibers, commercially available underthe name Saran and marketed by DoW Chemical Company, are also useful.The tetrafluoroethylene resins are usually superior to the other resinfibers for the purposes of this invention as they will withstandapproximately 500 temperature, although it is to be understood thatother fibers are satisfactory for lower temperature application and willeven be preferred for certain applications because of lower cost andgreater ease in manufacture, such as nylon and polyethylene fibers. Thefibrous materials of this invention and the low friction surfacesprepared therefrom uniquely differ from solid bodies or sheets of theSame material because in certain applications, where sheet materialshave completely failed, fibers of that same material uniformly disposedand positively retained against flow on a similar surface have proved tobe satisfactory. The low friction fiber material in most cases does notbond readily with other materials, and in order to assure a good bond,bondable fibers are woven on the reverse side of the Woven low frictionfibers so that on the working face of the resulting Woven material alowfriction Surface will be provided and on the opposite face a bondablesurface will be present. Thus assurance is had that the low frictionfibers will be retained in position at all times since the bondablefibers are positively retained in position on the supporting material.For example, inherent resistance to bonding is possessed by thepolymeric fiuorocarbon resins and these fibers have been successfullyWoven on a conventional backing material such as cotton, rayon, nylon,wool, glass and the like, in such a manner that the working face carriesuniformly distributed fluorocarbon resin fibers on its surface. ln anyarrangement fibers are employed on the working face having low frictioncharacteristics, while dissimilar fibers or cords on the opposite facehave bondable charactertistics. This procedure facilitates theattachment of such fibers to the supporting body material directly bysuch fiber material or by the use of adhesion or bonding materials whichwill secure the cotton, rayon, wool, etc., thereto. Thus, the lowfriction face may be applied to a fabric having a bondable back face, tothe face of a webbing material if body is desired back of the lowfriction face, or to the inner or outer sides of a fabric in sleeveform, with the opposite side having the bondable face.

In bearing and sealing applications, failure occurs when the lowfriction surface materials cold flow, spall or seize during use andvalthough it has not been completely experimentally established, it isthought that the fibers are successful for the purpose of this inventionrelative to sheet materials because the fibers are much stronger intensile strength than sheet material fabricated from exactly the samesubstance. For example, in the case of tetrafiuoroethylene resins, thetensile strength is approximately twenty-five times greater than thetensile strength of the material in sheet form. The exceedingly hightensile strength of the tetrafiuoroethylene resin in fiber or filamentform provides substantial resistance against cold flow which occurs whenthe resin is in sheet or block form. Adding to this substantial'resistance against cold fiow by the fibers and the secure anchorprovided by the bondable cords woven to oneface of the fibers, assuranceis had that a permanent low friction surface is provided which resistswear, flow and deterioration.

The low frictionY materials of this invention have differentcharacteristics and properties but may be broadly defined as materialslubrications and in dry form. The polymeric fluorocarbon resins'arestable and useful at temperature through 500. F. and Veven ashigh as 600in certain cases, and it' amasar can well be appreciated that suchfibers backed with glass fibers will withstand high temperatures withoutdeforrn-r ing While retaining the low friction characteristics.

in the copending application of Charles S. White, Serial No. 396,893,tiled September 8, 1953, now US. Patent No. 2,835,521, for Ball JointBearing Structures, a ball joint is illustrated having one element madefrom a plastic insert the shape of the ball which is set by theapplication of heat after the insert is shaped to the adjacent surfaceunder pressure. When the compound fabric was secured to the insert witha surface of Teiion engaged with a mating polished surface, the jointwas operated more than 600,000 times in the absence of a lubricant `andunder a load of 2200 pounds per square inch without any visible wear onthe insert or surface. Under such a load the joint was expected to havea high breakaway characteristic, requiring a substantially greater forceto initially move the joint than that required to move it thereafter.The breakaway load of the joint hav ing the Teflon surface abovedescribed was surprisinvly low, requiring no noticeable amount ofapplied force over that to move the joint after breakaway. For example,ball joints such as those employed in an automobile having a load of1200 pounds per square inch thereon have la static and dynamic forcerequirement to produce movement of 1%. ft. pounds in each instance.After 300,000 cycles of operation, the force requirement in bothinstances was l ft. pound and at 600,000 cycles the force requirementwas l/s ft. pounds in both instances. In this test, a small amount ofgrease was applied to the metal face of the socket at the time ofassembly. No wear or damage to the surfaces was found when examining thejoint parts after the 600,000 cycles of operation.

Accordingly, the main objects of the invention are: to provide acompound fabric having a low friction surface on one side and a bondablesurface on the opposite side; to provide a strip of webbing with a faceof low friction fibers which is woven directly thereto; to provide asleeve of fabric material having on the inner or outer face a lowfriction fabric material and on the opposite face a bondable material;to provide a compound fabric with a face of low friction ber woventogether to form a compact continuous surface having on one side thereofexposed cords of bondable material; and, in general, to provide a fabrichaving a face of low friction characteristics which is simple inconstruction and economical of manufacture.

Other objects and features of novelty of the invention will bespecifically pointed out or will become apparent when referring, for abetter understanding of the invention, to the following descriptiontaken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a plan view of a fabric of the low friction type havingbondable cords secured to one face thereof;

FIG. 2 is an enlarged sectional view of the structure illustrated inFIG. 1;

FIG. 3 is a sectional view of a ball forming a joint, with a woven lowfriction fabric face of a strip of webbing, embodying features of theinvention;

FIG. 4 is a sectional view of a strip of webbing ernployed in the socketof FIG. 3 before pressure is applied thereto;

FIG. 5 is an enlarged plan view of the low friction webbing materialillustrated in FIG. 4;

FIG. 6 is a sectional view of the woven webbing material illustrated inFIG. 5;

FIG. 7 is a perspective view of a sleeve Woven to have a low frictionsurface on the inner face thereof, made in accordance with the presentinvention;

FIG. 8 is an enlarged View of the weave employed to construct thesleeve, as viewed within the circle 8 of FIG. 7, and

FIG. 9 is a sectional view of the structure illustrated in FIG. 8,Ytaken on the line 9-9 thereof.

It is to be understood that various types of weaves may be employed forforming the compound fabric having on one side thereof the low frictionfibers and on the opposite side thereof the bondable fibers. Forexample, when the compound fabric is employed for faces of seals, thebodies of which have elastomeric properties, the cornpound sleeve mustbe able to expand and contract with the elastomeric material and shouldoffer no resistance to the application of pressure by the material ofthe seal. The weaves herein illustrated therefore are merely shown byway of example and not by limitation, as it is to be understood that indifferent applications different types of weaves will be employed.

For a flat fabric, reference may be had to FIGS. l and 2 wherein onemethod of weave is illustrated for producing the compound fabric havingthe substantially solid surface of the low friction fibers and thebondable backing layer, substantially all of which is made up ofbondable fibers. The lo-w friction fibers 10 form the warp of thefabric, while the fibers 11 form the ller thereof. The layer of bondablecords I2 is disposed parallel to the warp cords 10 and is retained byhaving each of the filler cords 1I pick up a bondable cord 12 at certainspaced points, herein illustrated as every fourth cord. The nextadjacent filler cord 13 picks up the next adjacent bondable cord 14 andskips three of the adjacent bonding cords before picking up the nextadjacent cord 14. The third filler cord 1S will pick up the next bondingcord 16 and will skip three bonding cords and pick up the next adjacentbonding cord I6. The fourth filler cord 17 will pick up the nextadjacent bonding cord 18 and will skip three of the bonding cords untilit picks up the next adjacent bonding cord 13. rl`hus, it will be seenthat the greatest percentage of the bonding cord will be exposed forbonding purposes and will leave the opposite face of the fabricsubstantially solid with the warp cords 10 and the filler cords Il oflow friction material. A compound fabric is thus provided having lowfriction fibers on one face and bondable fibers or cords on the oppositeface.

In FIGSB to 6, a webbing 21 is illustrated having on the face 22 thereofthe low friction bers. The face of the webbing is woven somewhat as asleeve about a plurality of lengths of stuffer cords 23 which fill theinterior of the sleeve and provide body to the resulting web. The oneply or face 22 has warp cords 24 and ller cords 25 of the low frictionfibers woven together at the same time that warp cords 26 of cotton orother material are woven with ller fibers 27 of cotton or other materialon the other ply or face. The front and rear woven portions of thewebbing are tied together by the cords 28 which securely retain the freelengths of cords 23 in position therebetween. The low friction webbingmay be employed, as illustrated in FIG. 3, within a channel-shapedsocket 29 which retains the webbing under pressure, with the lowfriction face encompassing the ball portion 31 of the resulting balljoint. In such an arrangement, it may be desired to have the body cords23 coated with a wax, grease, graphite and like materials so that thecords will readily shift when the anges of the socket 29 are forceddownwardly into parallel relation, as illustrated in the figure. Thisproduces the desired amount of pressure between the face of low frictionmaterial of the webbing and the ball which permits the initial movementof the ball without requiring a substantial breakaway force, permittinga uniform movement under a uniform pressure. It is to be understood thatwhen desired, the opposite face of the webbing, being of cotton or likematerial, may be bonded to the socket 29 or other body materials towhich the low friction material will not bond.

In FIGS. 7, 8 and 9, a further form of the invention is illustrated,that wherein a sleeve 33 is woven from low friction bers and a cord ofbondable material. In this arrangement, the cord of bondable material 34skips four cords of the low friction material 35 as it is continuouslywound into cylindrical form. The cord 34 engages an adjacent cord 35each revolution while skipping the cord 35 prorly engaged so that as thecord 34 is wound in 3 cylindrical form at the end of five turns it willhave engaged each of the five cords 35 of all of the groups of the lowfriction cords 34. It is contemplated that a sleeve of such material maybe placed along the inner surface of bearing seals and the like, asillustrated in the copending application of Charles S. White, Serial No.544,944, filed November 4, 1955, for Sealing and Bearing Device HavingLow Friction Sealing Faces, now Patent No. 2,906,- 552. When thematerial of the seal has substantial movement, the sleeve of lowfriction material must contract or expand therewith, in which case theelastic hosiery Y weave known in the art is preferably employed inconstructing the sleeve. The sleeve of the low friction material wovenwith the elastic hosiery weave will not restrict the expansion andcontraction of the body material of the seal. It was pointed out abovethat the various weaves were herein illustrated by way of example andnot to be considered limiting since other types of known weaves maybetter be employed for certain applications of the resulting fabric,webbing and sleeve materials. It is to be understood that the wovenmaterial of low friction bers may be applied to strips of packingmaterial to form a face thereon which, when compressed about a stem orrod within a packing gland, will have low friction engagement therewith.Such a packing material could be provided by the webbing 23 if all ofthe outer surface contained the low friction fibers. It is also to beunderstood that the low friction bers could be retained upon a layer ofmaterial to which it is secured by bonding, weaving or the like toprevent the cold flow of the iibers when subjected to pressure. Thespecific examples recited herein are not to be considered limiting asthe low friction fibers may be secured to a layer of material by othermeans not specifically recited, and the weave employed in producing thefabric may take any form known in the art to be suitable.

What is claimed is:

1. A woven fabric having spaced plies forming opposite faces thereof,one of said plies having threads of tetrailuoroethylene material thereinto provide a low friction surface on the outer face thereof, the otherof said plies having threads of bondable material therein to provide abondable surface on the outer face thereof, a plurality of stuifer cordsin the space between said plies, and means for connecting said plies andretaining said stuffer cords in position.

2. The invention as defined in claim 1 wherein said fabric is formedinto a bearing sleeve with the threads of the tetrauoroethylene materialon one cylindrical face of the sleeve to provide a low friction bearingsurface.

3. The invention as defined in claim 1 wherein said connecting meanscomprises threads connecting each of said plies and retainingsaidrstufer cords in position.

References Cited in the file of this patent i UNTED STATES PATENTS Re.24,765 White Jan. 12, 1969 1,983,617 Ladon Dec. 11, 1934 2,208,090Whittier Iuly 16, 1940 2,248,761 Kosatka luly 8, 1941 2,312,089 GobeilleFeb. 23, 1943 2,461,626 Booth Feb. 15, 1949 2,542,297 Sunbury et al.Feb. 20, 1951 2,551,175 Smith May 1, 1951 2,681,667 Slaughter June 22,1954 2,683,637 Skillman et al July 13, 1954 2,804,886 White Sept. 3,1957 2,835,521 White May 20, 1958 2,845,959 Sidebotham Aug. 5, 19582,885,248 White May 5, 1959 OTHER REFERENCES Dupont: Textile FibersBasic Materials for Industry. (Copy -led in U.S. Patent Office .lune 21,1954; Division 21.)

1. A WOVEN FABRIC HAVING SPACED PLIES FORMING OPPOSITE FACES THEREOF,ONE OF SAID PLIES HAVING THREADS OF TETRAFLUOROETHYLENE MATERIAL THEREINTO PROVIDE A LOW FRICTION SURFACE ON THE OUTER FACE THEREOF, THE OTHEROF SAID PLIES HAVING THREADS OF BONDABLE MATERIAL THEREIN TO PROVIDE ABONDABLE SURFACE ON THE OUTER FACE THEREOF, A PLURALITY OF STUFFER CORDSIN THE SPACE BETWEEN SAID PLIES, AND MEANS FOR CONNECTING SAID PLIES ANDRETAINING SAID STUFFER CORDS IN POSITION.